On a remote, windswept ridge high above the treeline in the Coast Mountains of southwestern B.C., the dull hues of a brownish-green plateau suddenly give way to a bright-white, 50-metre-wide circle of stone.

It's the kind of sight that fires the imaginations of archeologists and UFO enthusiasts alike: Did some prehistoric aboriginal culture create a place of worship or a primitive astronomical observatory amid the clouds and jagged peaks of the Chilcotin Range, about 300 kilometres northwest of Vancouver?

Or — why not? — did an away party of alien explorers build a signal station there or even a spaceship landing site?

Two scientists from Canada and Britain were sufficiently intrigued by the "unusual, near-circular ring of stones" and its "uncertain origin" that they probed the strange feature and have just published their findings in the Canadian Journal of Earth Sciences.

The researchers, Geological Survey of Canada emeritus scientist Andrew Okulitch and Michael Czajkowski of the U.K.'s Open University, were alerted to the circle by Czajkowski's sister, the well-known B.C. writer and off-the-grid wilderness guide Chris Czajkowski. She operates a backwoods retreat in the area and had snapped an aerial photo of the unusual rock formation.

The two geologists examined the site as a private research project, hoping to understand how it came to be. And their conclusion — which will come as a letdown to both history buffs and believers in extraterrestrial visitation — is that the stone circle is the result of natural forces, an extraordinarily geometric gift left in the wake of a retreating glacier about 10,000 years ago.

"Although I expect a lot of people would be disappointed or even reluctant to learn that the circle was a natural feature and not built by aliens or lost unknown cultures," Okulitch told Postmedia News, "what I find exciting are the strange and wonderful ways in which nature can work, and the challenges we are confronted with in trying to figure them out."

Ancient aboriginal sites elsewhere in B.C. have produced "smaller stone rings" and associated artifacts, the researchers wrote in the published paper. But "an anthropogenic origin was dismissed" at the Chilcotin site "since there is no evidence of stacking" of the white stones, some of which weigh several tonnes.

"The harsh climate and absence of sustenance at 2,000 metres elevation in post-glacial times likely discouraged occupation or even travel in the region," the co-authors added, "and no obvious astronomic or spiritual reason for such a structure can be imagined, even if a supply of unique stones was available in the immediate area."

Instead, Okulitch and Czajkowski surmised that the rocks became stranded on an isolated glacial mass at the end of the last Ice Age, sliding off piece by piece around the edge of the frozen pillar until it melted away and left the stone circle behind.

"I think it is highly unlikely that a circle made from huge boulders that show no signs of having been worked by tools could be man-made in a region that offers so little sustenance or reasons for such a construction," said Okulitch, noting that the nearest significant source of light-coloured rock is located more than two kilometres from the circle.

"I've just returned from a trek in southern Peru, so I know what humans can accomplish when it comes to moving big stones, but the Incas lived in a fertile region and could muster tens of thousands of people to do the work," Okulitch said. "Nothing like that ever existed in prehistoric B.C., as far as we know, and if it did, one would expect more evidence for such a civilization than one lonely circle."